Method and system for detecting a change in at least one telecommunications rate plan

ABSTRACT

A call schedule is received that includes a plurality of sample calls to be made by an automated calling station. The plurality of sample calls are automatically placed on the network using the automated calling station. At least one final billing record corresponding to the at least one completed sample call is received. The call data is processed to determine billed cost data. The billed cost data is compared to the previous cost data and a change in the rate plan is detected based on the comparison of the billed cost data to the previous cost data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following patent application, thesubject matter of which is hereby incorporated by reference thereto:

"Method and System For Generating a Billing Record," filed on Apr. 25,1997 and having Ser. No. 08/845,173, now U.S. Pat. No. 5,920,613.

TECHNICAL FIELD

The present invention relates to telecommunication networks, and inparticular, to systems and methods for detecting the change in atelecommunication service rate plan used for generating a subscriber'sbilling record.

BACKGROUND ART

Until recently, tariffs were legally required by the F.C.C. and stateregulatory commissions for all telecommunications services. The publiccould rely on published tariffs to keep track of long distance servicesand rates. Rate information could be obtained manually by consulting thepublic tariffs or by using service providers who provide rate summariesand updates. Recently, the F.C.C. has eliminated the requirement ofF.C.C. tariffing. In addition, many state regulatory agencies arechanging their tariffing requirements.

The absence of many tariffs and the lack of generally available publicinformation has created the need to generate and automatically detectchanges in the service plans and rates for long distance carriers.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the appended claims.However, other features of the invention will become apparent and theinvention will be best understood by referring to the following detaileddescription in conjunction with the accompanying drawings in which:

FIG. 1 presents a flowchart representation of a method in accordancewith the present invention;

FIG. 2 presents a block diagram representation of a system in accordancewith the present invention;

FIG. 3 presents a block diagram representation of the operation of aprocessor in accordance with one embodiment of the present invention;

FIG. 4 presents a flowchart representation of a method in accordancewith a further embodiment of the present invention;

FIG. 5 presents a flowchart representation of a method used inaccordance with an additional embodiment of the present invention;

FIG. 6 presents a flowchart of a method used in accordance with oneembodiment of the present invention; and

FIG. 7 presents a block diagram representation of a system in accordancewith the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The various embodiments of the present invention yield severaladvantages over the prior art. In one embodiment, the telecommunicationsystem and method of the present invention generate a billing recordbased on a plurality of rate plans. A subscriber subscribes to a singlelong distance carrier. A method and automated system are presented thatallow a subscriber's transaction record to be processed by the pluralityof rate plans corresponding to plurality of different carriers and anamount is deducted from the total of the lowest plan to insure that abilling record is generated that corresponds to an amount that is lowerthan the amount that would be billed under any of the plurality of rateplans.

In an additional embodiment, the telecommunication system and method ofthe present invention can automatically detect a change in a carrier'srate plan based on the bills generated by automated calling. This allowsstored rate plan information to be updated in a timely matter.

FIG. 1 presents a flowchart representation of a method in accordancewith the present invention. In particular, the present inventionpresents a method of generating a billing record for at least one of theplurality of subscribers for use in a network for providingtelecommunication service to a plurality of network subscribers. Themethod begins by receiving a transaction record as shown in step 100.The transaction record includes transaction data corresponding to atleast one telephone call placed by a subscriber.

In a preferred embodiment, the transaction data corresponds to aplurality of telephone calls placed by the subscriber during a timeperiod, such as a monthly billing period. The plurality of telephonecalls include on calls for which a toll or charge is associatedincluding intra LATA toll calls, inter-LATA toll calls and internationaltoll calls. The transaction data includes, for each of the telephonecalls, the time of day, date, duration and destination of the call.

In step 102 transaction data is processed by a plurality of rate plans,each rate plan generating a toll amount corresponding to the telephonecalls of the transaction record. In a preferred embodiment, each of theplurality of rate plans correspond to the service rates for one of aplurality of interexchange carriers that are not the subscriber's chosencarrier. Optionally, at least one of the plurality of rate planscorrespond to a optional calling plan corresponding to one of theinterexchange carriers. In this fashion, a toll amount can be estimatedthat corresponds to the amount each interexchange carrier, and moreovereach optional calling plan of each interexchange carrier, would bill forthe telephone calls in the transaction record. The rate plan structureand the service rates can be estimated based on the results for aplurality of sample calls. Service rate information derived frompublicly available information can also be used, if available.

In step 104 the toll amounts from each of the plurality of rate plansare compared to determine a lowest toll amount. In step 106 an amount xis deducted from the lowest toll amount to form a final toll amount. Ina preferred embodiment of the present invention, x is a value calculatedas a percentage of the lowest toll amount. In this embodiment, the finaltoll amount is therefore some predetermined percentage, less than 100%,of the amount that would be billed by the least of the interexchangecarriers. However, in an alternative embodiment of the presentinvention, x is a constant value. In this alternative, the final tollamount is a fixed amount less than 100%, of the amount that would bebilled.

In step 108, the billing record is generated for the subscriber based onthe final toll amount. In a preferred embodiment, this billing record istransmitted to a bill generator that receives the billing record andformats and prints a billing statement for transmittal to thesubscriber. In this embodiment, the billing record would include thetransaction data in addition to the final toll amount. The billingrecord can further include the calculated toll amount for one or more ofthe interexchange carriers. This provides the subscriber withinformation to demonstrate the amount of savings by using the chosencarrier over the other interexchange carriers.

FIG. 2 presents a block diagram representation of a system in accordancewith the present invention. In particular, FIG. 2 presents a system forimplementing each of the methods and features described in conjunctionwith FIG. 1 described above. Network 122, in a preferred embodiment ofthe present invention, is a public switched telephone network (PSTN)that provides telecommunication service to a plurality of networksubscribers having respective customer premises equipment 120.

Interface unit 124, coupled to the network 122 receives a transactionrecord, the transaction record including transaction data correspondingto at least one telephone call placed by at least one subscriber. In apreferred embodiment, the PSTN generates transaction records in a mannerthat is know to those of ordinary skill in the art. Call data isrecorded on tapes at the originating central office. These tapes arecollected periodically and mailed to a tape receipt center that includesinterface unit 124. Interface unit 124 reads the tapes and converts thetransaction records from Automated Message Accounting (AMA) or CallDetail Record (CDR) format into Electronic Message Interface (EMI)format. This process is also the subject of tape control, time controland error processing procedures that insure that all of the recordedtransaction records are present.

In a preferred embodiment of the present invention, the transactionrecords are originally processed at a predetermined basic billing rateand stored in a customer toll master file that is updated daily untilthe end of a billing cycle. At the end of the billing cycle thesetransaction records, for each customer, are transferred to the processor126.

Processor 126, in communication with the interface unit 124, processesthe transaction data by a plurality of rate plans, each rate plangenerating a toll amount corresponding to at least one telephone call.Processor 126 then compares the toll amounts from each of the pluralityof rate plans to determine a lowest toll amount. Processor 126 deductsan amount x from the lowest toll amount to form a final toll amount, andgenerates the billing record for at least one of a plurality ofsubscribers based on the final toll amount.

In a preferred embodiment, processor 126 is implemented using an IBMmainframe computer running DB2 application software. Rate plans areimplemented in software that, for example, calculates toll amounts as afunction of: the approximate call mileage--determined from theoriginating NPA-NXX and the terminating NPA-NXX; thejurisdiction--intrastate (interLATA or intraLATA), interstate (interLATAor intraLATA) or international; the time of day and day of week of thecall; the duration of the telephone call; and the billing increment--thefirst minute or additional minutes; in accordance with the actual rateplan of the carrier. Optional calling plans are also implemented insoftware that calculates, for instance, the toll rate based on the timeof day, day of week and the total monthly call volume in accordance withthe actual optional calling plan of the carrier.

Bill generator 128, in communication with the processor 126 receives thebilling record for at least one of the plurality of subscribers andformats and prints the billing statement. There are numerous companiesthat specialize in providing this service to telecommunication serviceproviders. These companies typically use mainframe computers coupled tohigh-speed printers to perform this function. One such company isInternational Billing Services of Eldorado Hills, Calif.

FIG. 3 presents a block diagram representation of the operation of aprocessor in accordance with one embodiment of the present invention. Inparticular, the operation of processor 126 is represented. Processor 126processes the transaction data by a plurality of rate plans 132, eachrate plan 132 generating a toll amount corresponding to at least onetelephone call. Processor 126 then uses comparator 134 to compares thetoll amounts from each of the plurality of rate plans 132 to determine alowest toll amount. Processor 126 uses summing block 136 to deduct anamount x from the lowest toll amount to form a final toll amount thatcan be used to generate the billing record for at least one of aplurality of subscribers based on the final toll amount.

FIG. 4 presents a flowchart representation of a method in accordancewith a further embodiment of the present invention. In particular, thisembodiment presents a method, used in a network for providingtelecommunication service to a plurality of network subscribers, fordetecting a change in a telecommunication service rate plan. This methodcan be used in conjunction with the method presented in association withFIG. 1 and FIG. 2 to detect rate plan changes from other interexchangecarriers in order to update a rate database, for instance a rate plandatabase used for generating a billing record.

In step 140, a call schedule is received. The call schedule includes aplurality of sample calls to be made by an automated calling station. Ina preferred embodiment of the present invention, the call scheduleincludes a call destination, a call time and a call duration for each ofthe plurality of sample calls. The call schedule further identifies oneof a plurality of carriers and potentially an optional calling plan foreach of the plurality of sample calls. In this preferred embodiment, thecall schedule is derived to place calls that test various parameters ofa carrier's rate plan by placing calls at different times of day, ofdifferent durations, and to different destinations.

In step 142, the plurality of sample calls are automatically placed onthe network using the automated calling station. In a preferredembodiment, the automated calling station includes a plurality oftelephone lines, each telephone line having an assigned carrier andwherein the step of receiving a call schedule includes receiving aplurality of call schedules, each of the plurality of call schedulescorresponding to one of the plurality of telephone lines. In analternative embodiment of the present invention a single call scheduleincludes sample calls that designate a particular carrier andpotentially an optional calling plan. Each sample call is associated toone of the plurality of telephone lines by matching the one of theplurality of carriers for the sample call to the assigned carrier, andpotentially an optional calling plan, for the one of the plurality oftelephone lines. In a further alternative, a single call scheduleincludes sample calls that designate a particular telephone linedirectly.

In addition, in a preferred embodiment, each of the plurality of samplecalls is reattempted up to y times if not completed. In a furtherembodiment, an error record is generated for reporting to a systemadministrator if at least one of the plurality of sample calls cannot becompleted after y re-attempts. The generated error record includes thecall schedule information corresponding to the call that could not becompleted.

If at least one of the plurality of sample calls is completed the methodproceeds to step 144 and at least one final billing record correspondingto at least one completed sample call is received. The final billingrecord includes call data for at least one completed sample call. In apreferred embodiment, the call data includes billed cost data thatcorresponds to the billed cost of the call, the call destination, thecall time and the call duration, the carrier, a call mileage, anoriginating LATA and a terminating LATA for each of the completed samplecalls.

In step 148 the billed cost data is compared to previous cost data thatcorresponds to the prior billed cost for a corresponding call. In step150 a change in the rate plan is detected based on the comparison of thebilled cost data to the previous cost data. In a preferred embodiment,step 150 includes comparing a previous cost element from the previouscost data to a corresponding billed cost element and detecting a changein the at least one rate plan if there is a difference between theprevious cost element and the billed cost element. In other words, ifthe bill reflects that a particular call has a different cost from acall from a previous billing cycle, such as the most recent billingcycle, having the same carrier, optional calling plan, duration, mileageband, time of day and day of week--this means that a change in thecorresponding rate plan has been detected.

In a preferred embodiment of the present invention, call data isgenerated, via the call schedule, for seven calls for each carrier,optional calling plan, time of day, and mileage band. In one embodiment,these calls are chosen to be 1, 2, 3, 4, 5, 6 & 7 minutes in length. Thechoice of 1, 2, 3, 4, 5, 6 & 7 minutes for the sample calls is notunique. Other sample call lengths can be used in conjunction with thepresent invention. In a second embodiment, the choice of 20, 36, 48, 60,72, 84 & 96 seconds is used.

In an alternative embodiment of the present invention, the call data foreach of the completed calls is used to generate a mean estimatedfirst-minute and additional-minute rate for each carrier, time of day,day of week, mileage band and optional calling plan. A statisticalanalysis is performed to generate a statistical metric that indicatesthe degree of difference between previous rate data (generated eitherfrom a previous bill or from publicly available information) and theestimated rate data. Hypothesis testing is used to accept or reject thenull hypothesis that the previous toll rate is correct. In thistechnique, the estimated toll rate is compared to a threshold, derivedfrom a predetermined level of statistical confidence (e.g. 95%confidence or 99% confidence) in order to determine whether or not thenull hypothesis can be rejected. A change in the rate plan is detectedif the estimated toll rate is greater than the threshold.

FIG. 5 presents a flowchart representation of a method used inaccordance with an additional embodiment of the present invention. Inparticular, the method of FIG. 5 includes steps 142-148 presented inassociation with FIG. 4 and further includes steps 160-166 that describea method for generating a final billing record.

In step 160 a printed billing record is received corresponding to thecompleted sample call. In a preferred embodiment, the printed billingrecord, in the form of a billing statement, is received directly fromthe carrier. In step 162, the printed billing record is opticallyscanned to obtain a plurality of electronic image data. In step 164, apreliminary billing record is generated in electronic form by performingcharacter recognition on the electronic image data. In step 166, thepreliminary billing record is processed to form the final billing recordby appending to the preliminary billing record the carrier, the callmileage, the originating LATA and the terminating LATA for the completedsample calls.

FIG. 6 presents a flowchart of a method used in accordance with oneembodiment of the present invention. In this embodiment, after a changein a rate plan has been detected for a particular carrier in accordancewith the methods of FIGS. 4 and 5, a new toll rate is estimated. In step190, the call data from that carrier and optional calling plan is usedto determine estimated rate data. This estimated rate data represents anestimate of the new toll rate that is in use by that carrier to generatethe bill for the completed sample calls.

In a preferred embodiment, call data for a particular carrier, time ofday, day of week, optional calling plan and mileage band is processedusing a logic algorithm that uses interval analysis to calculateestimated rate data that comprises estimated rate elements for theparticular carrier, time of day, day of week, optional calling plan andmileage band. These estimated rate elements are determined by generatingan upper and lower bound for the toll rate for the first minute of acall and for each additional minute. Either the upper or lower boundsfor each rate element can be used as estimates of the new rate element.For example, for a particular carrier, time of day, day of week,optional calling plan, and mileage band, the new first minute rateelement can be assigned to be the corresponding estimated upper boundand the new additional minute rate element can be assigned to be thecorresponding estimated lower bound.

In a preferred embodiment of the present invention, the amount billedfor the 1-minute call is used to generate an upper and lower bound onthe first minute rate--based on the fact that the bill is rounded to ortruncated to the nearest cent and also based on the possibility that theactual first minute rate can be a non-integer number of cents. The2-minute call data is then processed to generate an upper and lowerbound for the additional minute rate--based on the estimated firstminute upper and lower bounds. The 3-minute call data is then processedto refine (narrow) the bounds on the additional minute rate which canthen be used to refine bounds on the first minute rate.

The process proceeds to consider all of the data from the seven samplecalls and to iteratively narrow the upper and lower bounds on the firstand additional minute rates until the magnitude of the percentage changebetween iterations of the interval between the upper and lower bound,for either the initial or additional minute rate intervals, falls belowa threshold of 0.00001% or until the completion of a predeterminednumber of maximum iterations. At this point the final upper and lowerbounds are accepted and used, as discussed above, as new estimatedrates. For this iterative technique to operate, at least two samplecalls must be completed for the particular carrier, time of day, day ofweek, optional calling plan, and mileage band. In practice, thepredetermined number of maximum iterations can be chosen to be greaterthan the actual number of iterations required for convergence with the0.00001% threshold for a large set of sample data.

FIG. 7 presents a block diagram representation of a system in accordancewith the present invention. In particular, FIG. 6 presents a system forimplementing each of the methods and features described in conjunctionwith FIGS. 4, 5 and 6 described above.

Network 184, in a preferred embodiment of the present invention, is apublic switched telephone network (PSTN) that provides telecommunicationservice to a plurality of network subscribers. Call schedule interfaceunit 180 receives a call schedule, the call schedule including aplurality of sample calls to be made by an automated calling station.

Automated calling station 182 is coupled to the call schedule interfaceunit 180. The automated calling station 182 places the plurality ofsample calls automatically on the network 184. In a preferred embodimentof the present invention the automated calling station 182 is coupled toa plurality of telephone lines 190, each telephone line having anassigned carrier and potentially an optional calling plan and whereinthe step of receiving a call schedule includes receiving a plurality ofcall schedules, each of the plurality of call schedules corresponding toone of the plurality of telephone lines. In an alternative embodiment ofthe present invention a single call schedule includes sample calls thatdesignate either a particular carrier and optional calling plan. Eachsample call placed by the automated calling station is switched to oneof the plurality of telephone lines by matching the one of the pluralityof carriers for the sample call to the assigned carrier and optionalcalling plan for the one of the plurality of telephone lines. In afurther alternative, a single call schedule includes sample calls thatdesignate a particular telephone line directly.

In a preferred embodiment of the present invention the automated callingstation is implemented using a IBM Model P02 computer equipped with aDialogic D/160 SC-LS voice processing and analog interface board. Thespecific functionality of this computer system is controlled using IBMCallpath Directalk/2 voice processing software. The Directalk/2 softwareuses a node manager that sends programming commands, through Dialogictelephony hardware, to sixteen telephone lines that are connected to theboard.

In a preferred embodiment of the present invention, the sample calls areplaced on each individual line Q as follows. A call schedule is loadedonto line (call records are broken into time of day, day of weeksections within call schedule). The system checks the current time anddate and indexes to the next call record to be placed for line Q. Thesystem, through Dialogic circuit board functionality, tells line Q to gooff-hook. The system, again using functionality of D/160SC-LS board,checks for a dial tone on line Q.

If there is no dial tone, the system converts to slow down mode andattempts next call sequence after a specific time delay. If after y `nodial tone` conditions occur, the system will set an error flag to letthe system know that possible line trouble exists. If a dial tone isdetected, then the system places an outbound call (either direct dial,calling card, or toll free) again using D/160SC-LS board. The system,through dedicated detection device (1 per line), checks for call status.The call status is either: (1) successfully answered and held forcorrect duration; (2) successfully answered but held short of correctduration (3) busy signal on line; or (4) A-ring no answer. The systemthen records the call event in a Call Completion file (part of anon-board database).

For successful call attempts, the unique call record is not attemptedagain until the next bill cycle. For all other call status results theapplication will re-try the call record up to y attempts to achieve asuccessful attempt. If after y attempts the call has still not completedsuccessfully, the final call attempt is recorded in the Error Log fileand will not be reattempted until the next bill cycle. After all callsfor the calling schedule loaded for line Q have either been successfullycompleted or logged in the error log file (within a particular billingcycle), the system remains idle until the bill cycle for line Qincrements to next cycle.

Processor 188 receives at least one final billing record correspondingto at least one completed sample call, the final billing recordincluding call data and previous cost data for the completed samplecalls. Processor 188 compares the billed cost data to the previous costdata. A change in the rate plan is detected based on the comparison ofthe billed cost data to the previous cost data. In a preferredembodiment, processor 188 performs the techniques discussed inassociation with steps 146 and 148 of FIG. 4 and step 190 of FIG. 6.

A preferred embodiment of the present invention includes a bill scanner186 for receiving a printed billing record corresponding to thecompleted sample calls. Billing scanner 186 includes an optical scannerequipped with optical character recognition software for opticallyscanning the printed billing record to obtain a plurality of electronicimage data, and for generating a preliminary billing record inelectronic form by performing character recognition on the electronicimage data. In this embodiment the processor 188 receives thepreliminary billing record from the bill scanner 186 and processing thepreliminary billing record to form the final billing record by appendingthe carrier, the call mileage, the originating LATA and the terminatingLATA for the completed sample calls.

While the term day of week has been used throughout description above,it should be recognized that telecommunication billing systemstraditionally segregate days of the week only by the categories:holidays, Saturdays, Sundays, and other days of the week. However, moresophisticated segregation is possible as will be recognized by one ofordinary skill of the art.

While various embodiments of the present invention have been describedin conjunction with a public switched telephone network, theseembodiments could similarly apply to communications of messages overother telecommunication networks. In particular, other billing and rateplan monitoring systems, within the scope of the present invention, canbe implemented in conjunction within other such telecommunicationsnetworks.

The various methods described herein, in a preferred embodiment, areintended for operation as software programs running on a computerprocessor. One of ordinary skill in the art will recognize that otherhardware implementations such as application specific integratedcircuits, programmable logic arrays and other hardware devices couldlikewise be constructed to implement the methods described herein. Itshould also be noted that the software implementations of the presentinvention could be stored on a tangible storage medium such as amagnetic or optical disk, read-only memory or random access memory andbe produced as an article of manufacture.

Thus, there has been described herein a concept, as well as severalembodiments including a preferred embodiment, of a method and system forgenerating a billing record and for detecting a change in atelecommunication service rate plan. The various embodiments of thepresent invention herein-described have features that distinguish thepresent invention from the prior art.

It will be apparent to those skilled in the art that the disclosedinvention may be modified in numerous ways and may assume manyembodiments other than the preferred forms specifically set out anddescribed above. Accordingly, it is intended by the appended claims tocover all modifications of the invention which fall the true spirit andscope of the invention.

What is claimed is:
 1. In a network for providing telecommunicationservice to a plurality of network subscribers, a method of detecting achange in at least one rate plan used to generate a billing record forat least one of the plurality of subscribers, the method comprising thesteps of:receiving at least one final billing record corresponding to aplurality of sample calls to be made on the network, at least one of theplurality of sample calls being completed, the final billing recordincluding call data for the at least one completed sample call, the calldata including billed cost data; comparing the billed cost data toprevious cost data; and detecting a change in the at least one rate planbased on the comparison of the billed cost data to the previous costdata.
 2. The method of claim 1 wherein the at least one completed samplecall includes a call destination, a call time and a call duration. 3.The method of claim 2 wherein the at least one completed sample callfurther identifies one of a plurality of carriers for the at least onecompleted sample call.
 4. The method of claim 3 wherein the at least onecompleted sample call further identifies an optional calling plancorresponding to the at least one completed sample call.
 5. The methodof claim 3 wherein the at least one rate plan corresponds to one of theplurality of carriers.
 6. The method of claim 3 wherein the call dataincludes the call destination, the call time and the call duration, thecarrier, a call mileage, an originating LATA and a terminating LATA forthe at least one completed sample call.
 7. The method of claim 6 furthercomprising the steps of:receiving a printed billing record correspondingto the at least one completed sample call; generating a preliminarybilling record in electronic form; and processing the preliminarybilling record to form the at least one final billing record byappending the carrier, the call mileage, the originating LATA and theterminating LATA for the at least one completed sample call.
 8. Themethod of claim 1 further comprising the step of:processing the calldata to determine an estimated toll rate.
 9. The method of claim 8wherein the step of processing the call data includes performing aninterval analysis to generate an upper and lower bound corresponding toa rate element.
 10. The method of claim 9 wherein the step of processingthe call data includes estimating a first-minute rate element as thecorresponding upper bound and estimating an additional-minute rateelement as the corresponding lower bound.
 11. The method of claim 1wherein the step of detecting includes comparing at least one previouscost element from the previous cost data to a corresponding billed costelement and detecting a change in the at least one rate plan if there isa difference between the previous cost element and the billed costelement.
 12. In a network for providing telecommunication service to aplurality of network subscribers, a system for detecting a change in atleast one rate plan used to generate a billing record for at least oneof the plurality of subscribers, the system comprising:an automatedcalling station for placing a plurality of sample calls to be made onthe network, at least one of the plurality of sample calls beingcompleted; and a processor, for receiving at least one final billingrecord corresponding to the at least one completed sample call, thefinal billing record including call data for the at least one completedsample call, the call data including billed cost data for comparing thebilled cost data to previous cost data, and for detecting a change inthe at least one rate plan based on the comparison of the billed costdata to the previous cost data.
 13. The system of claim 12, wherein theat least one completed sample call includes a call destination, a calltime and a call duration.
 14. The system of claim 13 furthercomprising:a bill scanner coupled to the processor, for receiving aprinted billing record corresponding to the at least one completedsample call and for generating a preliminary billing record inelectronic form; and wherein the processor receives the preliminarybilling record from the bill scanner and processes the preliminarybilling record to form the final billing record for the at least onecompleted sample call.